Freighliner box truck

2007 P500 with MB 4 cyl 170?hp engine no power at all takes 3 miles to get to 60 mph. Frieghliner says that engine is putting out what its supposed to and that a code in the Allison trans is causing power loss. Took to Allison and had a harness replaced that put trans light out. Truck is exactly the same wont pull as it once did. Another symptom is a long crank period before starting. Hard to start with a short shut down, and overnight takes a loong crank period. Freighliner replaced check valve at head, same identical prob. Freightliner also says that HP level cannot be raised on this engine. True or not? This truck had engine replaced and now has 88000 on it, just does not have even close to the power it had. I know, I know it is a low hp pos but it should do what it did do! Asking for a friend who has a few of these trucks. This one is only one with problem.

 

No weight much at all. Its a Fed Ex truck. It does act like a boost problem but the stealer checked boost at wot and it shows 7.1 which they said was in range for that test method of sitting still with wot. Truck does not smoke out exhaust or road draft tube. Told them "just drive it, but dont pull out in front of someone!" They drove it around parking lot.

I'm told that the turbo and cooler have been replaced too.

 

No codes with the exception of the trans code mentioned earlier. That was erased when the harness was replaced.

Just talked to tech, he says it has 17# boost while driving. He said he thinks it has a fuel problem somewhere. As you said, it may have a fuel problem as a result not the cause. Hopefully he will pinpoint prob. He is just beginning his shift.

 

Supposedly, they have checked pressure. They charged owner for the line, fittings etc to make it up on another invoice. This is one of many trips to the shop with this piece.
Do you know what psi boost parameters are?

So we are looking at 26.4psi fuel at idle,36.7 @1200 rpm loaded,66 psi max. Will compare to their results.
Thanks for your ongoing concern and help. I will update when we hear what they say-----this time.